44 PLANT DISEASE 



and as the larger yield of grain was also sixteen 

 times better than the poorer one in its feeding 

 qualities, it is reasonable to think, if the whole 

 of the wheat of Great Britain was grown to 

 produce the maximum yield, that owing to its 

 greater flesh, fat, and heat-producing proper- 

 ties, any given quantity of it would go further 

 in feeding the people than the average quality 

 does to-day. 



Again, take the variation of iron in various 

 cereals. 



This is given by Watts in his Dictionary of 

 Chemistry, on page 826 



In wheat Fe 2 O 3 ranges between 3*3 & a trace 

 Oats 5-1 and O'i 



Barley 2'i O'l 



Rye ,, 2*2 



Maize 0*8 0-5 

 ,, xvice ,, ,, ,, 



All the other mineral constituents of cereals 

 and other foods have just as wide a range as 

 the iron. 



A similar variation is noticeable in the 

 potato 



